PLASTICS: Properties of plastics, Thermo Plastics, Thermo-Setting Plastics, Phenol formaldehyde

PLASTICS Plastics are commonly known as synthetic resins or polymers. In Greek terminology, the   term polymer comprises ‘poly’ means ‘many’ and ‘mers’ means ‘parts’. Thus, the term, polymer represents a substance built up of several repeating units, each unit being known as a monomer. Thousands of such  units or monomers join together in a polymerization … Read more

ORGANIC POLYMERS and ITS APPLICATIONS

ORGANIC POLYMERS Polymers consist of carbon chemically combined with usually with hydrogen, oxygen or other non- metallic substances. They are formed by polymerization reaction in which simple molecules are chemically combined into long chain molecules. Examples:  Nylon, Teflon, Polyethylene, PVC, Terylene, Cotton etc. Applications of organic polymers Polymers are used in making packings, pipes, covers … Read more

Semiconductors and Applications of Semiconductors

SEMICONDUCTORS Semiconductors are solid materials, either non-metallic elements or compounds which allow electrons to pass through them. These materials occupy intermediate position between conductors and insulators. Semiconductors usually have high resistivity, negative temperature coefficient of resistance and are generally hard and brittle. Examples: Germanium (Ge), Arsenic (As), Silicon (Si), Boron (B), Sulphur (S), Selenium(Se). Applications … Read more

Composites and Applications of Composites

COMPOSITES Composites are mixture of materials such as metal and alloys and ceramics, metals and organic polymers, ceramics and organic polymers. Examples: Vinyl coated steels, steel reinforced concrete, fiber reinforced plastics, carbon reinforced rubber etc. Applications of Composites These materials are used for making sports items, structures, and electrical devices.

CERAMICS MATERIALS AND ITS APPLICATION

CERAMICS MATERIALS Ceramic materials are non-metallic solids made of inorganic compounds such as oxides, nitrides, borides and carbides. Theses materials are fabricated by first shaping the powder with or without the application of pressure into a compact form and after that it is subjected to high temperature. Ceramics possesses electrical, magnetic, chemical and thermal properties … Read more

CUTTING TOOL MATERIAL: High Speed Steel, Cemented Carbides, Ceramics Tool, Carbides tool, Diamond

CUTTING TOOL MATERIAL Few material for cutting tools are generally used which are as follows. (i)  High Speed Steel These have superior hot hardness and it can retain the hardness up to 900°C. In    it tungsten produces martensite structure with other elements. It is three types 18-4-1 High Speed Steel. It has 18% tungsten, 4% chromium, … Read more

Heat Engine: Schematic Diagram of Thermal Power Plant, Schematic Diagram of Heat Engine, Schematic Diagram of Refrigerator and Heat Pump

Heat Engine  It is a cyclically operating device which absorbs energy as heat from a high temperature reservoir, converts part of the energy into work and rejects the rest of the energy as heat to a thermal reservoir at low temperature. Schematic Diagram of Thermal Power Plant Schematic Diagram of Thermal Power Plant The working … Read more

Second law of Thermodynamics: Kelvin-Planck Statement, Clausius Statement

 Second law of thermodynamics 1. Kelvin-Planck Statement  It is impossible to devise a cyclically operating device, which produces no other effect than the extraction of heat from a single thermal  reservoir  and delivers an equivalent amount of work.  Heat engine with single thermal reservoir is not possible. For a 1-T engine the thermal efficiency h=W/Q=1. No heat … Read more

Thermal Reservoir

Thermal Reservoir A thermal reservoir is a large system (very high mass x specific heat value) from which a quantity of energy can be absorbed or added as heat without changing its temperature. The atmosphere and sea are examples of thermal reservoirs. Any physical body whose thermal energy capacity is large relative to the amount … Read more